原生JS运动实现轮播图

//多物体多值运动+回调机制
function startMove(dom, attrObj, callback) {
 var key = true;
 var iSpeed = null,
  iCur = null;
 clearInterval(dom.timer);
 if (key) {
  dom.timer = setInterval(function() {
  //bStop用来判断是否开始执行回调函数
   var bStop = true;
   //判断传入目标值中的“键”类型是否为opacity
   for (var attr in attrObj) {
   //若要改变的样式为opacity，则将元素的opacity扩大100被进行操作
    if (attr === 'opacity') {
     iCur = parseFloat(getStyle(dom, attr)) * 100;
    } else {
     iCur = parseInt(getStyle(dom, attr));
    }
    //运动速度设为目标值减去当前值的一半，即当前状态离目标值越接近，运动速度越小
    iSpeed = (attrObj[attr] - iCur) / 2;
    //对速度进行取整
    iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);
    if (attr === 'opacity') {
     dom.style.opacity = (iCur + iSpeed) / 100;
    } else {
     dom.style[attr] = iCur + iSpeed + 'px';
    }
    if (iCur !== attrObj[attr]) {
     bStop = false;
    }
   }
   //当bStop为true时，元素的所有样式均已达到目标值，清理定时器并执行回调函数
   if (bStop) {
    clearInterval(dom.timer);
    typeof callback == 'function' && callback();
   }
  }, 30)
 }
 if (!key) {

 }
}
//用来获取元素实时的样式值
function getStyle(elem, prop){
 if (window.getComputedStyle){
  return window.getComputedStyle(elem, null)[prop];
 }
}

<div class="wrapper">
 <ul class="sliderPage">
  <li>
   <img src="./image/dog/阿拉斯加.jpeg"/>
  </li>
  <li>
   <img src="./image/dog/比熊.jpeg"/>
  </li>
  <li>
   <img src="./image/dog/边牧.jpeg"/>
  </li>
  <li>
   <img src="./image/dog/柯基.jpeg"/>
  </li>
  <li>
   <img src="./image/dog/阿拉斯加.jpeg"/>
  </li>
 </ul>
 <div class="btn leftBtn">&lt;</div>
 <div class="btn rightBtn">&gt;</div>
 <div class="sliderIndex">
  <span class="active"></span>
  <span></span>
  <span></span>
  <span></span>
 </div>
</div>

<style>
 *{
  margin: 0;
  padding: 0;
  list-style: none;
 }
 .wrapper{
  position: relative;
  margin: 100px auto 0;
  width: 600px;
  height: 360px;
  overflow: hidden;
 }
 .wrapper .sliderPage{
  position: absolute;
  left: 0;
  width: 3000px;
  height: 360px;
 }
 .wrapper .sliderPage li{
  width: 600px;
  height: 360px;
  float: left;
 }
 .wrapper .sliderPage li img{
  width: 100%;
  height: 100%;
 }
 .btn{
  position: absolute;
  top: 50%;
  width: 20px;
  height: 20px;
  color: #fff;
  text-align: center;
  line-height: 20px;
  background-color: #000;
  opacity: 0.2;
  cursor: pointer;
 }
 .leftBtn{
  left: 5px;
 }
 .rightBtn{
  right: 5px;
 }
 .wrapper:hover .btn{
  opacity: 0.8;
 }
 .sliderIndex{
  position: absolute;
  width: 100%;
  bottom: 10px;
  cursor: pointer;
  text-align: center;
 }
 span{
  width: 8px;
  height: 8px;
  background-color: #cccccc;
  border-radius: 50%;
  display: inline-block;
  margin-right: 5px;
 }
 .active{
  background-color: orange;
 }
</style>

var timer = null;
var sliderPage = document.getElementsByTagName('ul')[0];
var moveWidth = sliderPage.children[0].offsetWidth;
var num = sliderPage.children.length - 1;
var leftBtn = document.getElementsByClassName('leftBtn')[0];
var rightBtn = document.getElementsByClassName('rightBtn')[0];
var lock = true;
var index = 0;
var indexArray = document.getElementsByClassName('sliderIndex')[0].getElementsByTagName('span');
//索引切换
for (var i = 0; i < indexArray.length; i ++){
 (function(myindex){
  indexArray[myindex].onclick = function(){
   lock = false;
   clearTimeout(timer);
   index = myindex;
   changeIndex(index);
   startMove(sliderPage, {left: -index * moveWidth}, function(){
    lock = true;
    timer = setTimeout(autoMove, 3000);
   })
  }
 }(i))
}
//图片运动过程中改变index点的样式
function changeIndex(index){
 for (var i = 0; i < indexArray.length; i++){
  indexArray[i].className = '';
 }
 indexArray[index].className = 'active';
}
timer = setTimeout(autoMove, 3000);
//向左翻
leftBtn.onclick = function (){
 autoMove('right->left');
}
//向右翻
rightBtn.onclick = function (){
 autoMove('left->right');
}
//direction
//默认轮播方向 'left->right' / undefined
//点击left按钮 'right->left'
function autoMove(direction){
 clearTimeout(timer);
 if (lock){
  lock = false;

  if (!direction || direction === 'left->right'){
   index++;
   startMove(sliderPage, {left: sliderPage.offsetLeft - moveWidth}, function(){
    if (sliderPage.offsetLeft === - num * moveWidth){
     index = 0;
     sliderPage.style.left = '0px';
    }
    timer = setTimeout(autoMove, 3000);
    lock = true;
    changeIndex(index);
   });
  }else if(direction === 'right->left'){
   if (sliderPage.offsetLeft === 0){
    index = num;
    sliderPage.style.left = - num * moveWidth + 'px';
   }
   index--;
   startMove(sliderPage, {left: sliderPage.offsetLeft + moveWidth}, function () {
    timer = setTimeout(autoMove, 3000);
    lock = true;
    changeIndex(index);
   })
  }
 }
}